Tuesday, January 7, 2014

Rollercoaster weather and the Subnivian Zone

Just two days ago, this meadow was covered in 8 inches of snow and sealed in ice after there was freezing rain all day and the temperatures never rose above 32 until after dark. The next morning, we awoke to pouring rain and 56 degrees and this view -

As you can see, the meadows are mowed again after 3 years. Below you can see how the mice, shrews and voles had a field day in the upper meadow,

creating numerous trails in the air space or subnivian zone in just a couple of days. These trails were only present in the upper meadow and not the lower meadow, which has less plant diversity and consists mostly of golden rod, sweet gum trees and some reeds.

I'm re-reading Winter World by one of my favorite authors, Bernd Heinrich, who describes this zone very clearly. He writes that,

the temperature in this zone is "regulated" a degree or two of the freezing point" as snow acts as an insulator from above and heat rises from the earth below. In this space, the animals have freedom to move and search for food without the fear of being spotted by a predator.

By the end of the day, the temperatures have dipped back into the 30's and today, we awoke to 0 degrees and 25-35 mph winds, thus -21 with wind chill and blue skies.